R.I.P. Scout26
Well, sounds funny, but FlexSeal is supposed to be pretty chemically resistant. A quick google search seems to bear that up. You might want to try either the flex paste or flex tape, both of which also get good marks.
I wonder if those welding strips Bedlamite posted might do the trick here?
For the second one I would just get a couple pieces of galvanized strut and some angle braces of the correct size and through bolt them. One piece of metal inside and one outside.
If it broke there, it was only because it wasn’t properly backboned with some galvanized stock to begin with!You can still goop the cracks with some epoxy if you want to. I know people laugh about JB Weld anything but they have different flavors that really hold up well if used in the proper application. I know there is a model T block with a cracked cylinder out there somewhere that was JBW’ed and still running. Lower compression than modern stuff of course.